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Excess nitrogen is a pollutant and global problem that harms ecosystems and can severely affect human health. Pollutant nitrogen is becoming more widespread and intensifying in the tropics. There is thus a requirement to develop nitrogen biomonitoring for spatial mapping and trend analysis of tropical biodiversity and ecosystems. In temperate and boreal zones, multiple bioindicators for nitrogen pollution have been developed, with lichen epiphytes among the most sensitive and widely applied. However, the state of our current knowledge on bioindicators is geographically biased, with extensive research effort focused on bioindicators in the temperate and boreal zones. The development of lichen bioindicators in the tropics is further weakened by incomplete taxonomic and ecological knowledge. In this study we performed a literature review and meta-analysis, attempting to identify characteristics of lichens that offer transferability of bioindication into tropical regions. This transferability must overcome the different species pools between source information - drawing on extensive research effort in the temperate and boreal zone - and tropical ecosystems. Focussing on ammonia concentration as the nitrogen pollutant, we identify a set of morphological traits and taxonomic relationships that cause lichen epiphytes to be more sensitive, or more resistant to this excess nitrogen. We perform an independent test of our bioindicator scheme and offer recommendations for its application and future research in the tropics.
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Contaminantes Ambientales , Líquenes , Humanos , Biomarcadores Ambientales , Ecosistema , Nitrógeno/análisis , Monitoreo del Ambiente , Contaminantes Ambientales/análisisRESUMEN
The author of the original publication [...].
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The focus of this review is to present the current advances in Loop Heat Pipes (LHP) with flat evaporators, which address the current challenges to the wide implementation of the technology. A recent advance in LHP is the design of flat-shaped evaporators, which is better suited to the geometry of discretely mounted electronics components (microprocessors) and therefore negate the need for an additional transfer surface (saddle) between component and evaporator. However, various challenges exist in the implementation of flat-evaporator, including (1) deformation of the evaporator due to high internal pressure and uneven stress distribution in the non-circular casing; (2) heat leak from evaporator heating zone and sidewall into the compensation chamber; (3) poor performance at start-up; (4) reverse flow through the wick; or (5) difficulties in sealing, and hence frequent leakage. This paper presents and reviews state-of-the-art LHP technologies; this includes an (a) review of novel manufacturing methods; (b) LHP evaporator designs; (c) working fluids; and (d) construction materials. The work presents solutions that are used to develop or improve the LHP construction, overall thermal performance, heat transfer distance, start-up time (especially at low heat loads), manufacturing cost, weight, possibilities of miniaturization and how they affect the solution on the above-presented problems and challenges in flat shape LHP development to take advantage in the passive cooling systems for electronic devices in multiple applications.
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Malawi is listed as a Low-Income Food-Deficit Country (LIFDC) by the United Nations (UN), with high levels of poverty, malnutrition, and undernutrition. The maize grown in the Central Region of Malawi represents approximately a quarter of the total Malawian population's calorie intake, is a large source of local income, and a significant contributor to the country's Gross Domestic Product (GDP). While maize has been shown to be more resilient to climatic changes than many other grain crops, the predominantly rain-fed maize grown in Central Malawi has experienced many shocks from severe weather events in the past. Using the ensemble mean of 20 Regional Climate Models (RCMs), this study shows that temperatures in Central Malawi are projected to increase from the 1971-2000 baseline by between 1.4 and 1.6 °C by 2035 and 1.9 and 2.5 °C by 2055 under Representative Concentration Pathways (RCPs) 4.5 and 8.5 respectively, but precipitation projections are more uncertain. Using the UN Food and Agriculture Organization's (FAO) AquaCrop model, this study assesses the impact of future warming and three precipitation scenarios on two cultivars of maize planted on three separate dates in Central Malawi's summer planting season. The results indicate that if precipitation levels follow the ensemble average or maximum projection, then moving to a later planting date and a slower-developing cultivar may result in increasing yields compared to the baseline scenario. However, under a minimum precipitation projection, the results are less positive, with decreasing yields seen for both cultivars and all planting dates. The uncertainty around future precipitation therefore poses a significant risk of maladaptation and highlights the need for more robust precipitation projections in the area before climate model outputs are used as a primary driver for decision-making in Central Malawi's maize cultivation.
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Cambio Climático , Zea mays , Agricultura , Productos Agrícolas , MalauiRESUMEN
In the Anthropocene, in which we now live, climate change is impacting most life on Earth. Microorganisms support the existence of all higher trophic life forms. To understand how humans and other life forms on Earth (including those we are yet to discover) can withstand anthropogenic climate change, it is vital to incorporate knowledge of the microbial 'unseen majority'. We must learn not just how microorganisms affect climate change (including production and consumption of greenhouse gases) but also how they will be affected by climate change and other human activities. This Consensus Statement documents the central role and global importance of microorganisms in climate change biology. It also puts humanity on notice that the impact of climate change will depend heavily on responses of microorganisms, which are essential for achieving an environmentally sustainable future.
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Cambio Climático , Ecosistema , Gases de Efecto Invernadero/metabolismo , Actividades Humanas , Viabilidad Microbiana/efectos de la radiación , HumanosRESUMEN
Malawi is highlighted as one of the most vulnerable countries in the world to the effects of climate change. The large uncertainty around future climate change in the region remains a barrier to adaptation planning. Despite this high potential vulnerability, relatively little research has gone into determining how well available models represent this country's climate. This work therefore evaluates the ability of existing General Circulation Models (GCMs) and Regional Climate Models (RCMs) to hindcast climatic variables in Malawi at a resolution appropriate for climate change impact assessment and adaptation planning. We focus on monthly precipitation rate, and mean, maximum and minimum surface air temperature. This assessment compares available observed datasets against the outputs of six ERA-interim driven RCMs and 21 GCM-driven RCMs from the Coordinated Regional Climate Downscaling Experiment (CORDEX) initiative, and the 11 GCMs which form their boundary conditions. It was found that the performance of the RCMs is highly influenced by their boundary conditions. None of the individual or ensemble RCMs or GCMs assessed in this paper correlate well with the observed datasets for any of the assessed climatic variables. While, they do simulate the trending change in temperature variables well, the simulated outputs for precipitation are highly divergent. Based on these findings we suggest that either the ensemble RCMs or ensemble GCMs would be suitable for understanding projected temperature trends, with the RCMs providing better spatial resolution. However, none of the assessed models provide certainty over future precipitation trends in Malawi. As such we suggest that impact assessments and adaptation plans in Malawi will need to be designed and tested against a range of future precipitation scenarios. To improve modelling for Malawi it is recommended that regional climate models be improved for higher spatial resolution and inclusion of the impacts from large water bodies, including Lake Malawi.
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Since 1962 the Common Agriculture Policy (CAP) of the European Union (EU) has enabled payment of subsidy to some food producers for withdrawal of specific commodities - including fresh fruit and vegetables (FFV) - where market prices have fallen below a pre-set level. These deliberate withdrawals have led to large amounts of usable food (~60% of withdrawals) being destroyed on farms across the EU. Such wasted food incurs a significant climate change cost through its production-phase greenhouse gas (GHG) emissions. Here, we assess the magnitude of this FFV withdrawal and destruction, its spatial and temporal trends, and its associated GHG emissions between 1989 and 2015. We find the total mass of avoidable FFV losses occurring as a result of these EU CAP market interventions for this 26-year period to be 23.6Mt. The production-phase GHG emissions associated with the withdrawn FFV that was subsequently destroyed amount to 5.1Mt CO2e over this period. We also find that, with each successive Common Market Organisation (CMO) reform there has been a marked reduction (~95% between 1989 and 2015) in the quantity of such deliberate withdrawals. Surprisingly, however, whilst the absolute quantity of FFV withdrawn and destroyed has fallen, the proportion of withdrawals that is destroyed remained roughly static at an average of about 60%. Finally, to inform debate on action needed to address FFV specifically, and food loss and waste more generally, we highlight potential scenarios and mechanisms to reduce withdrawals, avoid FFV destruction and improve alternative use of withdrawn food in the future.
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Agricultura/métodos , Abastecimiento de Alimentos/estadística & datos numéricos , Gases de Efecto Invernadero/análisis , Agricultura/legislación & jurisprudencia , Contaminantes Atmosféricos/análisis , Cambio Climático , Monitoreo del Ambiente , Unión Europea , Abastecimiento de Alimentos/métodos , Frutas , Política Nutricional , VerdurasRESUMEN
India has been perceived as a development enigma: Recent rates of economic growth have not been matched by similar rates in health and nutritional improvements. To meet the second Sustainable Development Goal (SDG2) of achieving zero hunger by 2030, India faces a substantial challenge in meeting basic nutritional needs in addition to addressing population, environmental and dietary pressures. Here we have mapped-for the first time-the Indian food system from crop production to household-level availability across three key macronutrients categories of 'calories', 'digestible protein' and 'fat'. To better understand the potential of reduced food chain losses and improved crop yields to close future food deficits, scenario analysis was conducted to 2030 and 2050. Under India's current self-sufficiency model, our analysis indicates severe shortfalls in availability of all macronutrients across a large proportion (>60%) of the Indian population. The extent of projected shortfalls continues to grow such that, even in ambitious waste reduction and yield scenarios, enhanced domestic production alone will be inadequate in closing the nutrition supply gap. We suggest that to meet SDG2 India will need to take a combined approach of optimising domestic production and increasing its participation in global trade.
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Conservación de los Recursos Naturales , Producción de Cultivos , Abastecimiento de Alimentos , Grasas de la Dieta , Proteínas en la Dieta , Predicción , Humanos , India , Modelos TeóricosRESUMEN
There is a projected shortcoming in the fourth carbon budget of 7.5%. This shortfall may be increased if the UK pursues a domestic shale gas industry to offset projected decreases in traditional gas supply. Here we estimate that, if the project domestic gas supply gap for power generation were to be met by UK shale gas with low fugitive emissions (0.08%), an additional 20.4MtCO2e1 would need to be accommodated during carbon budget periods 3-6. We find that a modest fugitive emissions rate (1%) for UK shale gas would increase global emissions compared to importing an equal quantity of Qatari liquefied natural gas. Additionally, we estimate that natural gas electricity generation would emit 420-466MtCO2e (460 central estimate) during the same time period within the traded EU emissions cap. We conclude that domestic shale gas production with even a modest 1% fugitive emissions rate would risk exceedance of UK carbon budgets. We also highlight that, under the current production-based greenhouse gas accounting system, the UK is incentivized to import natural gas rather than produce it domestically.
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Research on loss & waste of food meant for human consumption (FLW) and its environmental impact typically focuses on a single or small number of commodities in a specific location and point in time. However, it is unclear how trends in global FLW and potential for climate impact have evolved. Here, by utilising the Food and Agriculture Organization's food balance sheet data, we expand upon existing literature. Firstly, we provide a differentiated (by commodity, country and supply chain stage) bottom-up approach; secondly, we conduct a 50-year longitudinal analysis of global FLW and its production-phase greenhouse gas (GHG) emissions; and thirdly, we trace food wastage and its associated emissions through the entire food supply chain. Between 1961 and 2011 the annual amount of FLW by mass grew a factor of three - from 540Mt to 1.6Gt; associated production-phase (GHG) emissions more than tripled (from 680Mt to 2.2Gt CO2e). A 44% increase in global average per capita FLW emissions was also identified - from 225kg CO2e in 1961 to 323kg CO2e in 2011. The regional weighting within this global average changing markedly over time; in 1961 developed countries accounted for 48% of FLW and less than a quarter (24%) in 2011. The largest increases in FLW-associated GHG emissions were from developing economies, specifically China and Latin America - primarily from increasing losses in fruit and vegetables. Over the period examined, cumulatively such emissions added almost 68Gt CO2e to the atmospheric GHG stock; an amount the rough equivalent of two years of emissions from all anthropogenic sources at present rates. Building up from the most granular data available, this study highlights the growth in the climate burden of FLW emissions, and thus the need to improve efficiency in food supply chains to mitigate future emissions.
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Abastecimiento de Alimentos , Gases de Efecto Invernadero/análisis , Geografía , Efecto Invernadero , HumanosRESUMEN
Soils are integral to the function of all terrestrial ecosystems and to food and fibre production. An overlooked aspect of soils is their potential to mitigate greenhouse gas emissions. Although proven practices exist, the implementation of soil-based greenhouse gas mitigation activities are at an early stage and accurately quantifying emissions and reductions remains a substantial challenge. Emerging research and information technology developments provide the potential for a broader inclusion of soils in greenhouse gas policies. Here we highlight 'state of the art' soil greenhouse gas research, summarize mitigation practices and potentials, identify gaps in data and understanding and suggest ways to close such gaps through new research, technology and collaboration.
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Agricultura/métodos , Secuestro de Carbono , Efecto Invernadero/prevención & control , Suelo/química , Agricultura/economía , Agricultura/tendencias , Dióxido de Carbono/metabolismo , Internacionalidad , Metano/metabolismo , Óxido Nitroso/metabolismo , Investigación/tendencias , IncertidumbreRESUMEN
The original report that plants emit methane (CH4 ) under aerobic conditions caused much debate and controversy. Critics questioned experimental techniques, possible mechanisms for CH4 production and the nature of estimating global emissions. Several studies have now confirmed that aerobic CH4 emissions can be detected from plant foliage but the extent of the phenomenon in plants and the precise mechanisms and precursors involved remain uncertain. In this study, we investigated the role of environmentally realistic levels of ultraviolet (UV) radiation in causing the emission of CH4 and other gases from foliage obtained from a wide variety of plant types. We related our measured emissions to the foliar content of methyl esters and lignin and to the epidermal UV absorbance of the species investigated. Our data demonstrate that the terrestrial vegetation foliage sampled did emit CH4 , with a range in emissions of 0.6-31.8 ng CH4 g(-1) leaf DW h(-1) , which compares favourably with the original reports of experimental work. In addition to CH4 emissions, our data show that carbon monoxide, ethene and propane are also emitted under UV stress but we detected no significant emissions of carbon dioxide or ethane.
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Dióxido de Carbono/metabolismo , Monóxido de Carbono/metabolismo , Hidrocarburos/metabolismo , Metano/metabolismo , Hojas de la Planta/efectos de la radiación , Lignina/metabolismo , Hojas de la Planta/metabolismo , Rayos UltravioletaRESUMEN
Manure generated by intensive livestock operations poses potential ecological risk in the form of water pollution and greenhouse gas emission. To assess the impact of biochar on coarse-textured soils under contrasting nutrient management regimes, a 55-d incubation was conducted using unplanted soil columns amended with manure, slurry, or fertilizer (plus unamended control), each with or without biochar applied at 2% soil mass (dry weight basis). Under repeated leaching, the cumulative NO emission from the columns was significantly affected by the presence of biochar ( < 0.0001), although these data were not normally distributed. Results indicated that the biochar-amended soils emitted significantly less NO than their unamended counterparts, with the exception of manure-amended soils. The presence of biochar increased the pH of column leachate by 0.08 to 1.70 and significantly decreased the cumulative amount of mineral N leached from the soil. The presence of biochar significantly increased the amount of PO-P in soil leachate, but there was no significant difference between the means for any of the amendments used on their own relative to their biochar-amended counterparts. The data demonstrate that biochar could potentially aid in the mitigation of NO emissions from certain soils and in N loss in leachate from soil amended with slurry, manure, or fertilizer used in livestock systems.
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Óxido Nitroso , Suelo , Fertilizantes , Estiércol , NitratosRESUMEN
SUMMARY: *Several studies have reported in situ methane (CH(4)) emissions from vegetation foliage, but there remains considerable debate about its significance as a global source. Here, we report a study that evaluates the role of ultraviolet (UV) radiation-driven CH(4) emissions from foliar pectin as a global CH(4) source. *We combine a relationship for spectrally weighted CH(4) production from pectin with a global UV irradiation climatology model, satellite-derived leaf area index (LAI) and air temperature data to estimate the potential global CH(4) emissions from vegetation foliage. *Our results suggest that global foliar CH(4) emissions from UV-irradiated pectin could account for 0.2-1.0 Tg yr(-1), of which 60% is from tropical latitudes, corresponding to < 0.2% of total CH(4) sources. *Our estimate is one to two orders of magnitude lower than previous estimates of global foliar CH(4) emissions. Recent studies have reported that pectin is not the only molecular source of UV-driven CH(4) emissions and that other environmental stresses may also generate CH(4). Consequently, further evaluation of such mechanisms of CH(4) generation is needed to confirm the contribution of foliage to the global CH(4) budget.
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Internacionalidad , Metano/análisis , Hojas de la Planta/metabolismo , Hojas de la Planta/efectos de la radiación , Plantas/metabolismo , Plantas/efectos de la radiación , Rayos Ultravioleta , Aerobiosis/efectos de la radiación , Biomasa , ClimaRESUMEN
Wetlands are the largest individual source of methane (CH4), but the magnitude and distribution of this source are poorly understood on continental scales. We isolated the wetland and rice paddy contributions to spaceborne CH4 measurements over 2003-2005 using satellite observations of gravity anomalies, a proxy for water-table depth Gamma, and surface temperature analyses TS. We find that tropical and higher-latitude CH4 variations are largely described by Gamma and TS variations, respectively. Our work suggests that tropical wetlands contribute 52 to 58% of global emissions, with the remainder coming from the extra-tropics, 2% of which is from Arctic latitudes. We estimate a 7% rise in wetland CH4 emissions over 2003-2007, due to warming of mid-latitude and Arctic wetland regions, which we find is consistent with recent changes in atmospheric CH4.
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Atmósfera/química , Productos Agrícolas , Metano/análisis , Oryza , Humedales , Archaea/metabolismo , Productos Agrícolas/crecimiento & desarrollo , Geografía , Gravitación , Metano/biosíntesis , Oryza/crecimiento & desarrollo , Estaciones del Año , Nave Espacial , Temperatura , Clima TropicalRESUMEN
Constructed wetlands are increasingly used for water pollution treatment but may also be sources of the greenhouse gas CH(4). The effect of addition of two potential inhibitors of methanogenesis - iron ochre and gypsum - on net CH(4) emissions was investigated in a constructed wetland treating farm runoff in Scotland, UK. CH(4) fluxes from three 15-m(2) wetland plots were measured between January and July 2008 in large static chambers incorporating a tunable diode laser, with application of 5tonha(-1) ochre and gypsum in May. CH(4) fluxes were also measured from control and ochre- and gypsum-treated wetland sediment cores incubated at constant and varying temperature in the laboratory. Ochre addition suppressed CH(4) emissions by 64+/-13% in the field plot and >90% in laboratory incubations compared to controls. Gypsum application of 5tonha(-1) in the field and laboratory experiments had no effect on CH(4) emissions, but application of 10tonha(-1) to a sediment core reduced CH(4) emissions by 28%. Suppression of CH(4) emissions by ochre application to sediment cores also increased with temperature; the reduction relative to the control increased from 50% at 17.5 degrees C to >90% at 27.5 degrees C. No significant changes in N removal or pH and potentially-toxic metal content of sediments as the result of inhibitor application were detected in the wetland during the study.
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Metano/química , Humedales , Sulfato de Calcio/química , Monitoreo del Ambiente , Compuestos Férricos/química , Efecto Invernadero , TemperaturaRESUMEN
Recent studies demonstrating an in situ formation of methane (CH(4)) within foliage and separate observations that soil-derived CH(4) can be released from the stems of trees have continued the debate about the role of vegetation in CH(4) emissions to the atmosphere. Here, a study of the role of ultraviolet (UV) radiation in the formation of CH(4) and other trace gases from plant pectins in vitro and from leaves of tobacco (Nicotiana tabacum) in planta is reported. Plant pectins were investigated for CH(4 )production under UV irradiation before and after de-methylesterification and with and without the singlet oxygen scavenger 1,4-diazabicyclo[2.2.2]octane (DABCO). Leaves of tobacco were also investigated under UV irradiation and following leaf infiltration with the singlet oxygen generator rose bengal or the bacterial pathogen Pseudomonas syringae. Results demonstrated production of CH(4), ethane and ethylene from pectins and from tobacco leaves following all treatments, that methyl-ester groups of pectin are a source of CH(4), and that reactive oxygen species (ROS) arising from environmental stresses have a potential role in mechanisms of CH(4) formation. Rates of CH(4 )production were lower than those previously reported for intact plants in sunlight but the results clearly show that foliage can emit CH(4) under aerobic conditions.
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Metano/biosíntesis , Nicotiana/efectos de la radiación , Pectinas/metabolismo , Rayos Ultravioleta , Etano/metabolismo , Etilenos/biosíntesis , Hojas de la Planta/metabolismo , Hojas de la Planta/efectos de la radiación , Especies Reactivas de Oxígeno/metabolismo , Luz Solar , Nicotiana/metabolismoRESUMEN
We investigated turnover of methane (CH4) in soils from a poorly drained UK forest. In situ, this forest exhibited a negligible soil-atmosphere CH4 flux, whereas adjacent grassland plots were sources of CH4. We hypothesised that the forest plots exhibited reduced anaerobic CH4 production through water-table draw down. Consequently, we exposed soil cores from under oak to high and low water-table conditions in the laboratory. Methane fluxes increased significantly in the high water-table (1925+/-1702 mug CH4 m(-2) h(-1)) compared to the low one (-3.5+/-6.8 microg CH4 m(-2) h(-1)). Natural abundance delta13C values of CH4 showed a strong depletion in high water-table cores (-56.7+/-2.9 per thousand) compared to methane in ambient air (-46.0 per thousand) indicative of methanogenic processes. The delta13C values of CH4 from low water-table cores (delta13C-46.8+/-0.2 per thousand) was similar to ambient air and suggested little alteration of headspace CH4 by the soil microbial community. In order to assess the CH4 oxidizing activity of the two treatments conclusively, a 13CH4 spike was added to the cores and 13CO2 production was measured as the by-product of CH4 oxidation. 13CH4 oxidation rates were 57.5 (+/-12.7) and 0.5 (+/-0.1) microg CH4 m(-2) h(-1) for high and low water-tables, respectively. These data show that the lower water-table hydrology treatment impacted methanogenic processes without stimulating methanotrophy.
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Metano/metabolismo , Suelo , Árboles , Agua , Isótopos de Carbono , Metano/químicaRESUMEN
Soils of all types and locations have generally served as the major sources of streptomycetous bacteria. These organisms are the source of nearly 80% of the world's antibiotics. Now, it is realized that Streptomyces spp. (within the group of prokaryotic filamentous bacteria known as actinomycetes) can exist as endophytes within the interstices of some higher plants. While it is sometimes possible to isolate one or two different streptomycetes from certain plants, most plants are free of these organisms. However, the snakevine (Kennedia nigricans) of the Northern Territory of Australia has yielded at least 39 different endophytic actinomycetes (95% of them being Streptomyces spp.) Most of these isolates possessed no detectable antibiotic properties, while at least seven had antibacterial and antifungal activities. Examination of eight selected cultures by scanning electron microscopy (SEM) as well as environmental scanning electron microcopy (FEI ESEM FEG) (FEI Company, Hillsobro, Ore., USA) revealed unusual patterns, structures, and features of the spores and hyphae of these microorganisms. For instance, as revealed by ESEM FEG for the first time, it has become obvious that extremely fine hair-like structures (average 25-49 nm with gold-coated specimens) exist on the spores and hyphae of some endophytic streptomycetes. The biological purpose of these hair-like protrusions is unknown. Both SEM and ESEM FEG can be effectively used as tools in identification and elucidation of the biology of these organisms. In addition, unusual colony morphology, observed with the unaided eye can very easily be used to distinguish some of these isolates since characteristic donut and pseudo-horn shaped colonies appeared in culture.